The easiest way to summon creatures in our minecraft server in Blockly is to create a main function, then in it, place a red command block then attach 'player me' then attach a green text block. In the text block, type summon zombie or whatever entity that works in version 1.9 or 1.9.2
To see a list of entities, click the blockly menu when you're in a badge look under minecraft < entities
Remember, all mods you create in learntomod need a function with the title of main (lowercase), otherwise the mod won't run. This is because main is the signal that tells the software to begin running mods.
Since you're a new user, I would recommend completing all the skills and drills < /learning to program badges before building anything new, then working on the badges outside of the skills and drills section. They'll teach you how to give you items, summon creatures, make particle clouds, etc.