TI 86 help

[BarTopDancer]

I suppose this is a very simple thing to do, yet for the life of me I cannot figure it out. I've searched about 20 different websites, read the manual and still cannot figure it out.

I need to know how to graph equations like 3^x=21 while solving for x. I need the x-intercept from the graph on the caculator.

So far this is what I have:

'graph'
y(x)
\y1=[equation here]

However I don't think that is correct.

Anyone?