Welcome! American wheat is a good first beer. Not too difficult, but still susceptible to high ferm temps. Find a place where the temp is about 65, or fashion a swamp cooler. Much warmer than that and the heat from the fermentation could push the temps up past 70 or so.
Sanitation is also critical once you've boiled the wort. That's when the bacteria and other things can infect the beer.
Make sure your water contains no chlorine or chloramine. Chloramine is commonly used as a drinking water additive and is less volatile than chlorine, and hence more difficult to get rid of. 1/4 campden tab will neutralize it though. For chlorine, just leave the water out over night, or give it a short boil before using. Not getting rid of the chlorine/chloramine will give your beer a plasticky smell and taste.
Other than that there are numerous things to read up on. I recommend the stickies in the beginners area and of course the online howtobrew.com is a great first step, as well as the various homebrewing books out there.
Most of all, Relax, don't worry and have a homebrew! (Or a commercial brew if you don't yet have any homebrew!) Have fun, everything will be fine!