What do you mean, have a try?

It means: hard, hard, hard, hard, fixed phrases.

I'm desperate. I'll be desperate if I try.

Just try, and then try; Come and have a try.

give it a try

Example:

1 There seem to be three good ways, and I will try.

Three seemingly good methods, I'll try another day.

Everyone was surprised, but no one dared to try.

At first, everyone was surprised to hear the news, but no one dared to try.