All commercial products sold as fertilizers (and some compost and compost manure), both synthetic and organic, have a guaranteed analysis printed somewhere on the package. It's three numbers such as 9-1-3. These are the percent by weight of nitrogen, phosphorous and potassium (N-P-K) in the fertilizer. Since you don't need P or K look for a fertilizer with a high first number which indicates it has a higher percentage of nitrogen.
Your soil test report should have given you a recommendation for how much nitrogen to add. Something like 15 lbs of nitrogen per 1,000 square feet.
Once you've settled on which fertilizer to use, calculate the size of the area you will be applying fertilizer to in square feet. For example let's say your garden is 200 sq ft.
So let's say at 15lbs/1ksq ft over 200 sq ft... 3lbs of nitrogen would b e needed. (15lbs/1,000sqft * 200sqft).
Next you need to figure out how many lbs of fertilizer to deliver the 3lbs of nitrogen. Using the example above 9-1-3 example above 1lb of fertilizer contains .09lbs of nitrogen. To get three lbs of nitrogen from this fertilize you would need 33 1/3rd lbs of fertilizer. (3lbsN/9%).
If you're using multiple fertilizer determine how much N each one provides and make sure the total will deliver the amount of N you need.