hi paul ,quite simple really.took me two days to do both my awning rails last month.1,remove plastic trim in rail.2,undo screws loads of them.3,clean van and rails of with white spirit and razor blade,get all the old mastic of.4,apply non setting bedding mastic to the join of the roof and side panel on the van.5,apply same mastic to rails above and below screw holes in a long continuase line.6,fit rails,get help to hold opposite end up .try not to move them once in place.7,put screws in,any bad holes move screw 1,inch either way .use 1,8th drill bit.8,refit trim. re,seth