today i went to the garden center and bought a wire mesh because after all i decided to do a scrog. i placed it in between the tops of the plants and the light what next do i top the plants or what.

If you are still in Veg its best to top the plants, however not all strains take well to topping, MOST are cool though. If you are in 12/12 already you shouldnt top them just let them go and try and sort of weave the plant into the mesh, basically trying to fill the screen with green, If you aint on 12/12 top the plants, veg them until they touch the screen (they should be about 2 ft high(ish)) then switch to 12/12.
All credit to you for giving it a go mate, it can be hard work but very satisfying when it works well.

there just a week into 12/12 and yes are about 2ft high.

the hps dual spectrum is ordered and on its way so will be switching to that the day it come and use the enviro to start off some female seeds.

btw do i need to lop off the bottom lots of leaves and branches under the screen of should i wait until i have a canopy.

Yep I agree totally with Sticky, you get some karma from me for some good advice

As for cutting back the bottom leaves, I wouldn't, the plant will take what it needs from them and they will die back naturally as your canopy develops.

I seem to remember trimming the leave tips of the lower branches to help oxidation or something - it's been a while - somebody tell me I am not crazy ...

Thanks for the Karma Webguy, it all helps!!

As for chopping of the branches, some say do it some say dont.
If you only have a single fan and this is blowing over the canopy then the air below the canopy can have ambient areas which will get moist as well as warm, the obvious problem is mould and disease. If you have topped the plant then the lower branches will catch up with the topmost as the plant takes on a more horizontal growth pattern. When the top of the plant reaches the screen decide which branches you want to keep and which you want to chop, I like to have 4 to 6 branches per plant going through the screen, (inc the topped stem). Please bear in mind I am no ScrOG expert, Ive done one and it went well (ish) for a beginner, but I done a lot of research and asked a lot of Qs before doing it, like yourself.

Edit to add - You def aint crazy Webguy I read that on loads of websites but havent tried it YET.