Gideon obeyed God (sometimes).
Great things were accomplished by God, through Gideon. Such as when the Midianites were defeated with only 300 men (Judges 6).
But Gideon did have moments where his obedience was not "second nature" or automatic, as seen in Judges 6:36-40. To paraphrase this is where Gideon asks God to "prove it to him" that he is going to be used by God to rescue Israel. His proof is that in the morning the wool will be wet but the ground will be dry. God proves it. Gideon still doesn't feel confident, so he asks again, but this time the opposite. The wool will be dry and the ground will be wet. Again God comes through. So Gideon is satisfied with this 'proof' or 'test' and he goes out to battle.
I think WE sometimes try to test God's work in our lives as well...
"I'll go on a mission trip"
"I'll pay my tithes more regularly"
"I'll start giving offerrings"
"you get me a raise or promotion"
"you erase my debt"
"you heal my body"
We shouldn't NEED to test God, or require proof from Him. We should simply love Him enough to obey His commands.
God wants to use us to do great things for His Kingdom, but first we need to be obedient to His Word to do that.
You may ask, well, what commands am I to obey? The answer lies in the Bible. Just start reading and a whole new world may be opened up to you. Even if you are not new to Bible reading, God can give you new 'eyes to see' what is there for you in this day and time. Have fun! ;)