Buy a sewing pattern. It will take you step by step through the process. That's how I learned. There are 'easy to sew' patterns that don't use a yolk and usually don't have cuffs. Think of summer beach shirts. A traditional dress shirt takes a little longer and will fit better. If you are a complete beginner an 'easy to sew' pattern wouldn't be that difficult. Unless you know the order to assemble the pieces you are going to have a hard time. There are cuts that need to be stabilized with stay stitching while you are working and some that need to be eased. It really isn't difficult. Just takes a little time the first time through. Once you know the process and the pieces then you can start improvising.