They don't make it easy, and they seem to be allergic to useful FAQs, but you can get the info if you know where to look.
Go to the Wageworks website. On the dashboard, click on your HSA. Then, from the left menu, click Investment Options. There will be a popup warning you that you're going to another site. Click yes, and then another window will pop up showing your HSA's investment account.
My account provider logs me in automatically, then has the tax forms under Summary -> Tax Forms. Generally these providers are big banks, so hopefully the last steps will be straightforward no matter who holds your money.
Make sure you click on your HSA, not any other account, on Wageworks. It will probably show a logo for some major bank. If you enter through another account, it won't have the Investment Options button you need.
