Hi Scotty , first I wanna say I'm in love with your YouTube videos!!! And yes , a little car trouble. 2008 chevy uplander that goes in reverse but not going forward and going into any gears but 3. Please help! Do I need a new transmission?

No. 1-1

Check the transmission fluid level. If you are lucky it is just low on fluid, so add the fluid specified for your car. If there is enough of it but it is really black/dirty, you might try changing the transmission fluid.

There is a gotcha because if the fluid has been bad for a long time then changing it may not do any good

But really, most likely, your transmission is already bad and you need to have it rebuilt or put in a used one or just get another car.