We use the conditional to show a possible situation based on another situation. For example:
If A happens, then B will happen.
The first conditional shows that something could possibly happen. Its structure is like this:
If + subject + present tense (or present progressive) ----, subject + will/may/can + base verb ----.
If it rains tomorrow, I will take my umbrella.
If you help me, we can finish earlier.
If the boys give the monkey a coin, it may dance for them.
Notice that each sentence above uses the present tense on the if side. But we could also use the present progressive if something is happening right now.
If he isn't working right now, he may want to come over for dinner.
We can also change the order of the sentence and put the if side on the second half. The only difference is that there is no comma.
I will take my umbrella if it rains tomorrow.
We can finish earlier if you help me.
The monkey may dance for the boys if they give it a coin.
He may want to come over for dinner if he isn't working right now.