My advice... Don't do-it-all-yourself. Novice and pro alike can benefit from each other in DIY. You might have the shed location leveled by a landscaper; get a referral to outsource the shed's foundation to a building subcontractor; you can even have the roof's trusses made by a local truss company and the shingles installed by a handyman or roofer.

For the masonry of the foundation we went out and bought 15 cinderblocks, and suplemented these with clay bricks that we got for free off of kijiji and some concrete pavestones from a neighbor's old patio.  Clay bricks can only be used above ground, other wise they will erode.  Looking back, it would have been easier to simply use cinderblocks and we strongly recommend it if you don't have other materials to get rid of.  Also, buy more mortar than you think you will need.  We ended up using a lot of mortar and if you have any extra you can always return it or pour it in the cinderblocks like we did to make the foundation even stronger.

Build the framework for all four walls. To account for the fact that the front and back walls are different from each other (due to the doorframe in the front) and the side walls must both be sloped (to prevent rain from collecting on the roof), each of these will have to be tackled somewhat differently. It’s easiest to construct the back first, the front second, and the two sides last, as shown in the numbered image below. See How to Frame a Wall for more information before you read the instructions below.[5]

how to build a shed