To send a message from the filters, simply click on the Contacts tab on the left-side navigation bar. Then use the filters available to hyper-target your Subscribers within your Keyword group. After selecting your filters, select your contacts in bulk that you wish to send your message to by clicking the check box above where your contacts are listed. Once your Contacts have been selected, click the blue "Send Message" button that appears above your contacts.

Compose your message as usual, then click the blue "SEND NOW" button to send it. (Be sure to not check your keyword box under "choose who to send" if you are sending a message to a filtered group, as you have already identified which group of contacts to message.)