As far as I am told you have to look into "filters" I have found this couple articles (one and two) on the net that may be of help. Snooping in the net, I have found this from an article online.
Filtering Emails in Gmail
If you are reading one of the emails from the extremely annoying person you wish you had never met, you can click the arrow next to the Reply button and choose “Filter messages like this” (being very careful not to accidentally reply with @!#$$% and open up a whole other can of worms).
Otherwise you can click the “Create a filter” link right next to the search boxes up near the top of the page…
If you chose “Filter messages like this” the From box will automatically be populated with the person’s email address, though you can write in their email address, or even their name. I’d go with the email address, and then click the “Next Step” button.
On the following screen which asks you which action you want to do on the filtered message, you can click the “Mark as read” checkbox, and then click on the “Delete it” checkbox. This will send their messages automatically to the trash can.
Clicking the “Create Filter” button will make this filter active, and you’ll find it listed under Settings \ Filters in case you want to edit or delete it.
You’ll notice that the message isn’t permanently deleted, as it will sit in the trash can for 30 days until it empties automatically. Somehow that seems appropriate.
Does it help??