We use the first conditional to talk about something that will happen (the result), if a particular condition (which is likely to happen) is met.
If you eat too much of that chocolate cake, you’ll feel ill afterwards.
If you’re not sure how to form a sentence like this, take a look at the BBC World Service’s web page.
I think this is a clear explanation of what we call the ‘zero conditional’: “We use the zero conditional to talk about something that will always happen (the result), if or when a particular condition is met.” So ….
“You can always read my blog posts if you have some time to spare.”
Read about this language point on the BBC website here.