How to install a plugin in WordPress

Good afternoon,

I have downloaded Smart Crawl plugin however I am uncertain on how to install it onto my wordpress platform to use for the website theme I already have?

I tried downloading it and then went into WordPress and clicked install plugin and clicked upload however I'm not sure which file(s) to upload.

Please could you go outline step-by-step instructions on how to do this.

Many thanks for bearing with me!

Very best,

Thomas