raise everything on the high E string two frets and work out how to play the low E and A strings in a higher octave
"The man that hath no music in himself, nor is not moved with concord of sweet sounds, is fit for treasons, stratagems, and spoils. The motions of his spirit are dull as night, and his affections dark as Erebus. Let no such man be trusted."

To convert guitar tab to banjo:
You can use a chord chart and, as Free bird mentioned, best transposed into the key of G for most banjos.
The guitar and the banjo (and the piano...and other instruments) are tuned to "concert pitch" or C--where a C is the same note for all instruments. For other instruments with different pitch ranges, like the sax, or trumpet, etc., C is a different note.
I just play the chords to convert my guitar tab in banjos.