If you are selling on eBay via Turbo Lister or the like at present and relying on that income migrate across gradually to build up confidence.
Start with simple listings and stay with eBay checkout for now.
Then you move on to scheduling and then to the use of the store, profiles and templates.
Whatever you do don't just jump in the deep end as eBay doesn't refund fees for mistakes
If you are very much a novice build up slowly, I did over a few month, the tools are quite extensive and there is a learning curve. We can advise and answer specific questions but it would be too much or us to teach you everything you need to know.
So start with the basics as above, work through the relevant tutorials, check the FAQ's and these boards when something puzzles, it takes a bit of effort but is well worth it.
