Can any body help me i am new here.

I am new on themeforest. I have a good knowledge about html, css and lessfreamwork. how can i start from here?
Please help me.

You need to be good in design … if not, try to find peoples from PSD section and cooperate with them.

yes i have knowledge about html, css, lessfremwork and bootstreep. and also use jquary but i have no good knowledge about jquary. can i start work here?
i can convert psd to html.

Yes, you can work here. Basically if you wish to sale template. You need to make them and submit and then it will be reviewed. If accepted then it will be up for sale.

But there is a minimum standard that you have to follow. Checkout the help section for more details.