Ok, What are you wishing to convert? In to what? IE. a basic Space Marine into "Lord Fire Doom of the Fire Lords chapter of Space Marines"
2. What experience do you have using hand tools? Green stuff? Do you have any hand tools (what are they) and green stuff (modeling putty)?
3. Can you draw/ are you a visual person. I think that this helps to break down the 'pieces' of a model into their basic shapes and find the right stuff to convert with/ sculpt. A drawing helps you cement your goal in your head and is useful to figger out possible problems before hand.
4. What is your 'inspiration'? Pictures help of the 'final product' that your looking to emulate. We can help you here online, and there are quite a few threads/blogs that can give you information on the basics, and there are some of the smartest folks in the 'field' that can and will give you free advice if you ask right here, you just have to ask and show them what you are looking to do. If you are more of a hands on person/ see someone do something and your good, have you tried you local hobby/game shop? Some if not most have a night or a group that gets together to model and paint, and most are very open to new members.