Yes you can bail yourself out of jail after you've been arrested and processed through the jail system.
To be able to bail yourself out of jail you must either have the full cash amount of bail money with you or have the money on a debit or credit card to be able to bail yourself out of jail.
If you have the money then you can let the jail staff know that you want to bail yourself out of jail if you're allowed bail.
Not everyone gets bail and some people may be held in jail without bail for some crimes but most times you will get a bail amount so that you can get released from jail.
If you don't have the cash to bail yourself out of jail then you can contact a bail bondsman to come and post bail on your behalf.
You'll usually need to have a percentage of the bail amount before the bail bondsman will bail you out of jail though.
If you don't show up at court then bounty hunters will be hunting you down and you'll be arrested again and likely not get bail the next time.