I have a 1988 Chevy ck1500 and when driving it will shift into 1st and 2nd but when it tries to shift into 3rd it just sounds like its in netral what can I do?

Sounds to me like either worn clutches or a hung shift valve.
Have you taken this to a transmission shop for a diagnosis or estimate?
How frequently has the fluid and filter been replaced?

Well when I was driving it spit up all the transmission oil all out of the dip stick hole so I'm assuming I need to rebuild the transmission is there any guide on what's the easiest way to remove it

That's a big task. First, removing the trans, and then doing the rebuild.
Many, many steps. Too many to simply list here.
Who will do the work? Any task specific tools or experience in this area?