There's still time to register to vote in the general election if you aren't already on the electoral roll. Encourage any youngsters or anyone else who is eligible - only takes 5 mins at https://www.gov.uk/register-to-vote . Deadline Monday 22nd May at 12 noon (well, 11.59pm!).
To add a post - click on plus sign at top right (if it is not there, you are not signed in - see link at top of page). To later edit it, display the post, and click on pencil at top right.
If you wish to give somebody your contact details, you may prefer to do so by personal message (click on little envelope at top of page, then on plus sign) rather than putting it in a post which is visible to everyone.