A very famous ZZ Top tune, there are 2 guitar parts. This is the Rhythm guitar, which is very easy and beginner friendly. All you need for the whole song are these 4 powerchords:
C5 - Bb5 - F5 - G5
To learn about barre / powerchords, watch this video. The rhythm is 99% played using regular palm muted downstrokes. If you need to know what that means, watch this tutorial.
You can hear both guitar parts played together in this ActionTab, but we've lowered the lead guitar volume so you can focus more easily on the rhythm:
Intro / Verses - The lead guitar starts the song playing the signature riff. After a while, the Rhythm guitar joins in the background with the C5 powerchord. Then proceeds to the verses:
C5 (stay on the C5 from the Intro) - Bb5 - C5 (once only) - F5 - C5 - Bb5 - G5 (once only) - F5
End the verses with this progression:
G5 - F5 (once only) - G5
Use open stabs for the last 2 chords: Bb5 - C5
That covers the cast majority of the song. The only other song sections are very simple:
Solo 1 Backing - Play the C5 for AGES, then open strike Bb5 - G5. Then palm mute again: F5 - C5 - F5 - C5. End by open striking Bb5 - G5
The rest of the song only repeats the above sections.