@luis_pr is giving you good advice here on sulfur and buying a pH kit. It's what I do.
I've found sulfur slow to act. You dig it into the soil but it takes a while to kick in. But it also persists, so that is good.
The other thing you need to consider is the pH of the water you use. It doesn't help to acidify the soil if the water is alkaline (like mine is). Test your water and if it is alkaline there are ways to acidify your water as well.
Good luck!
