How we cite our quotes: The poem is 159 lines long, so we just cite by line number.
Quote #1
These beauteous forms (22)
The "forms" the speaker is describing are the shapes of the cliffs, trees, cottages, et cetera that he describes in the first stanza. "Forms" seems very non-specific, though. Why doesn't he say "landscape"? Considering the personal relationship he develops with this particular scene, it might seem odd that he uses such an impersonal word to describe it.
Quote #2
more like a man
Flying from something that he dreads, than one
Who sought the thing he loved. (70-72)
The speaker describes his younger self, the boyish William, running like crazy around the mountains of Wales. Maybe the younger William did have a chip on his shoulder ("something he dreads") from which he was trying to run away. Or maybe he was just running for the sake of running, with no purpose at all, because he hadn't yet learned to appreciate nature intellectually.
Quote #3
For nature then
(The coarser pleasures of my boyish days,
And their glad animal movements all gone by)
To me was all in all. (72-75)
The "coarser pleasures" and the "glad animal movements" describes the younger William's crazy running around from the more mature point of view of the speaker. Yes, he says, nature was everything to him back then, but his "pleasures" were "coarser," or less sophisticated, than they are now.