In order to get an interdict, you need to see a solicitor who will go before a Judge in the Sheriff Court, who will hear the application and decide whether it is suitable to issue an interdict. At the first hearing, the Judge will (more than likely) issue an interim order with a hearing in seven days time to issue the interdict.
Legal aid is available for certain types of interdicts providing you fit the criteria but it is not available for defending them.
If you or your solicitor feels that your partner's behaviour amounts to a criminal offence then you should contact Police Scotland by dialling 101 to report it.
Occasionally an interdict will carry a power of arrest. Your solicitor will make sure that the police have a copy of it so that they can take action if the interdict is breached.