Two tips:
1. Buy Sporty's VFR Communications DVD. It's worth every penny for a student pilot and it covers uncontrolled airports as well as Class B, C, and D airports.
2. At an uncontrolled airport, there is almost no such thing as the wrong thing to say. The key is to maintain situational awareness of where others are,
primarily with your eyes, and to use the radio to
supplement both your own situational awareness and that of others in the area. There are some best practices to follow, and you'll develop habits as you go so it is important to practice good habits. But don't ever be paralyzed by wanting to get it right.
For example, I'd rather hear you say "
Podunk, we're a Cessna ten miles to the east landing at Podunk" and then call again to say "
Podunk traffic, Cessna 3-2-bravo is on left downwind for runway 1-0, Podunk" when you're in the traffic pattern than any of the following (only one of which contains a slight exaggeration of something I've actually heard on the radio):
Perfectly communicate "Podunk traffic, Cessna 3-2-bravo is 1-0 miles east, planning left downwind runway 1-0, Podunk" and then not say anything else until you clear the runway.
"Podunk area unicom, any traffic in the area please advise." This conveys nothing at all other than that you haven't been listening to the radio and don't plan to look with your eyes.
"Podunk traffic, Cessna 3-2-bravo is clear of the active." There's no such thing as "the active" at an uncontrolled airport, so this conveys no information at all.
"Podunk traffic, Cessna 3-2-bravo is over the final approach fix for runway 1-0, Podunk." This conveys the right information but only to pilots familiar with the instrument approaches for runway 10 at Podunk, which is likely to be about one in five pilots.
"Podunk...uh...." Minutes pass. "Podunk area traffic, this is...uh..." More time passes. "Podunk area, we're crossing midfield, and ... hold on....uh..." More time passes. "...ixture, prop, seatbelt. Podunk, Cessna, uh..." Moments later. "Podunk traffic, Cessna 3-2-bravo is clear of the active."
"Podunk traffic, Cessna november-5-4-2-3-bravo is ten miles east, four thousand three hundred twenty feet, planning to cross midfield and then enter left downwind for runway 1-0, landing, full stop, Podunk. Podunk traffic, Cessna november-5-4-2-3-bravo is six miles east, four thousand one hundred five feet, planning to cross midfield and ... wait, no, we won't need to cross the field to get on left downwind. So we're going to just enter a left downwind for runway 1-0. Landing at Podunk, full stop. Podunk. Podunk traffic, Cessna november-5-4-2-3-bravo is four miles east, three thousand feet, planning left downwind for runway 1-0, full stop, Podunk. Podunk traffic, Cessna november-5-4-2-3-bravo is entering left downwind for runway 1-0, two thousand eight hundred feet, full stop, Podunk. Podunk traffic, Cessna november-5-4-2-3-bravo is passing midfield over the fuel pumps on the north side of the ramp, east side of the FBO, left downwind for runway 1-0, two thousand six hundred feet, left traffic, full stop for runway 1-0, Podunk. Podunk traffic, Cessna 5-4-2-3-bravo is left downwind turning base for runway 1-0, descending through two thousand four hundred feet, full stop, runway 1-0, Podunk. Podunk traffic, Cessna 5-4-2-3-bravo is base turning left final for runway 1-0, about a 3-mile final, maybe 2, runway 1-0, full stop, Podunk. Podunk traffic, Cessna 5-4-2-3-bravo is on short final for runway 1-0, full stop, Podunk. Podunk traffic, Cessna 5-4-2-3-bravo is down on runway 1-0, Podunk. Podunk traffic, Cessna 5-4-2-3-bravo is slowing through 40 knots, runway 1-0, Podunk. Podunk traffic, Cessna 5-4-2-3-bravo is turning around, going to back taxi runway 1-0 / 2-8, Podunk. Podunk traffic, Cessna 5-4-2-3-bravo is back taxiing runway 1-0 / 2-8, taxiing to the fuel pumps on the east side of the FBO, north side of the ramp, Podunk. Podunk traffic, Cessna 5-4-2-3-bravo is clear of runway 1-0 / 2-8, taxiing to the fuel pumps on the east side of the FBO, north side of the ramp, Podunk. Podunk traffic, Cessna 5-4-2-3-bravo is at the fuel pump next to the FBO, shutting down, Podunk." This talkative fellow was the only plane in motion at an airport 100 miles away that shares our CTAF frequency, and I'm not sure he ever let off the mic once from 10 miles out until he shut off the avionics master. I listened to him talk to himself from before I started my descent until shortly before I had to turn on the runway lights, thankful that he didn't go around and keep the airwaves busy for another 10 minutes and thereby cause me to go around over a dark runway.
So don't worry. You are probably already doing better than all of those guys.