I can answer this not line by line, but every couple/few lines .  And keep in mind this was written in 1807, NOT in this day and age.  Looking at it now we could really tie in a lot of technology that takes us away from nature.

The first four lines shows how the fast-paced Industrialized West was not taking time to appreciate nature.  "Getting and spending, we lay waste our powers" says that we are too materialistic; we waste our opportunities to love and respect nature and all that it holds.  We just earn and spend on a daily basis.

The next four lines describe the aspects of nature that we take for granted every day.  We ignore the breezes and the winds that surround us each day.  We don't appreciate the sea and all the power and beauty that it holds.  Because of this he says, "we are out of tune; it moves us not."  Most people just don't "get it."

The first link explains the ending for you.  Wordsworth would rather be a Pagan--one who worships nature--than one of the many individuals who passes through life without realizing the love and passion that nature holds for us.

This poem is actually a sonnet by William Wordsworth.  Written in the Romantic thematic style, there are many elements which make it distinctive to Wordsworth's beliefs and systems.  From the opening lines, the speaker seeks to create a realm where individuals are able to perceive and "see" reality and nature without the clouded lens of society and social connection.  This notion of sight is directly identified in line 3 with the line, "Little we see in Nature that is ours."  The poem continues to explore this idea of being able to strip away the vision in front of the speaker, the socially determined and dictated view of the world, and seek a vision that is closer to the "good, the true, and the beautiful" notion of the world.  In striving for this vision, the speaker suggests that one has to move away from conformity and socially driven conceptions, and seek out a more individualistic one that is closer to the "truer" sense of nature.