To be able to proceed with an application you will need to be registered with the following (Registration is quick & FREE)
Sell2Wales https://www.sell2wales.gov.wales/ and etenderwales https://etenderwales.bravosolution.co.uk/home.html
There is an online application called an ITT (Invitation to Tender). The link to the tendering document is here - ITT: itt_102671 - Support Services framework for Young People, Children and Families - Round 4 (etenderwales eTendering Portal) (bravosolution.co.uk)
If you wish to find out more information, then please contact Sharon Titley on sharon.titley(at)powys.gov.uk. Once you have started your online application then Powys will not be able to have any direct contact with you, however there will be a message portal facility available for any queries.