The paste I had was unlabelled but had HCl so I assume it was "acid". The solder just said lead free with no content listed so I do not know if it had silver.

I read some posts suggesting "Oatey Safe Flo Silver Solder with HTC paste" I found the solder but the kit had No.95 tinning flux which seemed better as it has powder metal in it too. Home Depot for $11.94 (even has a brush and sand paper included too).

When I solder copper pipe, the flux is inside the fitting so it does not burn; just heat the outside and melt the flux, and then add solder to joint. In this case, it is all open. Do I heat beside the area or directly to the region to solder?

Seems my technique needs help so comments welcome.