Up on the right top corner, there is a button called Sell.
Click on it
Read all the dropdowns.
Make a test listing.
Come back and ask specific questions.
Very generally:
SELL WHAT YOU KNOW: KNOW WHAT YOU SELL
Spelling counts
Take clear pictures
Do not picture what you are not selling.
Describe as if you had no pictures.
Use metric measurements for shipping.
Use metric and Imperial measurement for describing.
Don't guess at shipping costs.
Don't believe everything eBay's Customer Service tells you.
Avoid underpricing. Don't list for less than you would be content to recieve.