With adequate height under the eaves of your home, an attached carport is fairly easy to construct.
Step 1 - Check with Your Local Government for Required Permits
Building a carport without a permit is illegal in many areas of the country. Fines could be levied or worse, they could force you to remove anything you've built until a permit is obtained. If a permit is required ask what documents you'll need to produce. Blueprints and site plans are common for this process.
Step 2 - Lay Out Your Carport
Use stakes and string lines to locate front, end, sides and where the support posts will be. Ensure your layout is square with the existing building before you begin.
Step 3 - Anchor the Support Header
Use lag screws to attach the support header to the existing building 1/2", plus the thickness of any siding and trim, from the building's edge.
Step 4 - Dig Your Post Holes and Set Your 4x4 Support Posts
Using post hole diggers dig the holes for your posts. Make sure the posts are level and plumb, then use quick set concrete to anchor them into the ground. Use 2x4 braces to support the posts as the concrete cures.
Step 5 - Install the Two End Boards (Outer Rafters)
Use joist hangers to anchor the outer rafters to the support header on one end and lag screws to the 4x4 post at the other. Do this for both ends.
Step 6 - Install the Front Beams
Install the front beams, one on either side of the 4x4 posts, along the front (i.e., the long side of the carport) using 16d nails.
Step 7 - Install the Rafters
Using joist hangers to anchor the rafters to the support header and rafter ties to secure them to the front beams install the rafters 24" on center.
Step 8 - Tee Nail 2 x 4 Blocking between the Rafters
Cut the tee nail blocking between the rafters on 24" centers
Step 9 - Cut and Attach Corner Bracing at Each 4 x 4 Post
Attach corner braces at 45 degree angles to anchor each 4x4 post to the end or front beams (depending on the 4x4 post location) using 16d nails.
Step 10 - Final Touches
Install the fascia and metal roofing. Paint or trim the fascia with siding. Pour concrete or spread gravel for the carport's floor.