I have a 1994 Ford thunderbird with the 4.6l v8 the problem is when I put it in drive it don't want to go forward until I put it up to 3500 rpms but still don't shift but will shift into reverse fine

You need to stop trying to put it in gear. At least until you check the transmission fluid. Automatic transmissions have 2 identical sets of ( Bands )-[forward & reverse] that press together by way of hydraulic pressure. Between the 2 sets of bands there is an amazing set of gears called A PLANETARY GEAR SYSTEM. If you do not have enough transmission fluid in the transmission the bands will not be pressed together tight enough and they will began to slip against each other. The result will be a burnt transmission. You can burn the forward bands and still have reverse. Or you can burn the reverse bands and still have forward. It sounds to me like you may have already burnt the forward bands. Pull the dip stick and smell the fluid. If the bands are burnt you can usually smell a burnt smell. The bad news is that once the bands start slipping against each other from lack of fluid pressure , it only takes about 30 seconds to completely wipe out a set of bands. My son could fix your car a heck of a lot cheaper than anyone you will talk to. His wife just passed from cancer. He was primary care giver so he had to quite his job. She is gone so now he must get back to work. We are in NC. You could let me know where you are.

How hard is it to change the bands

Or could. The transmission got to hot maybe

He is right... pull the dipstick and put some oil on your fingertip. Smell it. Look at the color of it... does it looked burned? What is the level of the fluid in the transmission. Be sure to check it according to the mfg instructions. At the absolute best, you could be very low on fluid but not have ruined the transmission yet. good luck.