i beam question

Your project is certainly doable but you need to give a whole lot more information particularly what is the ovehead span going from the doorway to the house plus the load factor for your area (snow can be awfully heavy)

But a bigger deal will be getting by any local building authorities. They will have definate ideas of what standards you should be following and who should be resposible for those standards. Read: get a structural engineer to sign off on them.

You are not likely to get a def> i have an enclosed sunroom attached to the side of my house. i can enter

A microlam header or 2x header/steel plate sandwich is usually adequate for short residential spans. Get some qualified help.

A GluLam or LVL engineered wood beam should be sufficient, sistered with 1/4" steel plate if necessary. However, you need a structural engineer to tell you what size and other specs. If it is not signed off correctly, it is illegal in most places. Most companies that sell the beams almost always need the exact specs signed off, they can't just go on oral instructions alone.

Any of the W36 sections properly braced and supported should surely be enough for residential construction. I'm certain it can be made smaller; ask an architect or structural engineer to render a professional opinion as to how much smaller.