Database help on hosting service

About 6 months ago, I created my first website; it showcases some optimisation techniques applicable to the UK energy market. I successfully hosted it and then promptly forgot about it. In mid-December, I noticed a problem on the website and discovered a coding error (a faulty date-time), which I subsequently fixed. The problem arose when trying to 're-host' the website. The first time around, after Googling, etc, I figured out how to make my db connect to the host's MS SQL db server. I can characterise this as a 'fire and forget' - it worked, so I didn't bother with it any more. Now, when trying to make the connection again, I now characterise it as 'fumble and fail'...
So, what I need is really threefold:
1) help with a new db connection string so I can get the website running again,
2) a clear, step-by-step bullet point precis on how to do this, and
3) someone I can call for other, web-hosting technical issues, as they arise; I'm more of a technical developer/hacker and am new to website development, which I intend to continue with, and so will require some hand-holding, no doubt.

Thank you.