Learn basic rock n' roll chord progression. Early rock used two basic chord progression. Songs like "Earth Angel" and "Blue Moon used a I -vi-IV-V progression. The capital roman numerals refer to major chords, the lower case numeral indicates a minor chord. In the key of C the progression is C-Am-F-G. In key of G the progression is G-Em-C-D. The other common progression is the 12 bar blues progression which is I - I - I - I - IV - IV - I - I - V - VI - I. In the key of C this is C-C-C-C-F-F-C-C-G-F-C-C. These two chord progression will allow you to play hundreds of oldies songs on the electric guitar.
Find the tone. The electric guitar in oldies music utilized a clean guitar tone. This tone was still used on the early Beatles recordings. Plug your guitar into a Fender or Vox tube amp and set the treble control to about six or seven. The clean tone was replaced by a heavier and overdriven guitar sound become popular in the mid and late 1960s.
Start learning songs. Go online to Betty Lou's Oldies which is located at Bettylou.zzruss.com. Betty Lou provides the chord progressions and lyrics for hundreds of oldies, ranging from pop an rock, to country and crooners.
Put a band together. Find a bass guitarist and drummer. Complement the band with other musicians such as a saxophone and piano player. Practicing alone in your room is a good place to start, but playing with a band is the best way to really learn how to play oldies on the electric guitar.
Book gigs and play out. Oldies bands are very popular. Show everyone what you have learned and have fun.