Can someone help me to know more about wines and learn the art of wine tasting?

Depending on where you live, there are often multiple
opportunities to educate yourself in the art and knowledge of enjoying
wine.

Paid
opportunities:

Community College Classes: any community
college with a culinary arts department likely offers a wine-tasting class.  I took one
for fun one year.  It was $40 for 6 weeks, and we met every Thursday night for 2 hours. 
The teacher brought between 7 and 10 different varietals for us to taste and also
provided fruit, chocolate and cheese.  She would show us how different foods brought out
different flavors in the wine.  We were taught what to expect in the aroma and on the
pallet.  It was a lot of fun and though no one walked away an expert, we certainly had a
better idea of what we liked or disliked at the end.

Free
opportunities: Most of the following examples do not have any overhead or "entry" fee,
however, most expect that you purchase a glass or a bottle of wine before you
leave.

Upscale grocery stores: Many (such as Whole Foods
and The Fresh Market) have weekly wine tastings at a scheduled time.  Even if you do not
live near one of these stores, check with any grocery store near you that has a wine
section and ask if they do tastings.  Usually these are free, and in my experience, not
very busy.  You can get lots of personal attention and have questions answered.  Also,
it is very low key, so do not be afraid to admit you know nothing about wine.  Ususally
this kind of customer is exactly who they are hoping
for.

Wine warehouses and/or wine-bars: Usually in slightly
bigger cities you can find stores completely devoted to wine (like Total Wine and More)
as well as restaurants or wine-bars that specialize in wine and wine-pairing.  These
places are just as excited to educate their customers as they are to sell them
something.  In addition to holding their own scheduled wine-tastings, I'm fairly certain
you can call ahead and schedule a "wine tasting party" yourself, especially if you are
bringing in a group of paying customers.

Local vineyards:
If you live in an area of the country where grape-vines grow and local wine is abundant,
you can take a tour of local vineyards.  Washington, California, Texas and North
Carolina are four states that I know of where you can pick up a map of local vineyards
at any tourism venue and visit the very place where the grapes
grow.

Do it yourself: In the novelty or "Food" section of
any major bookstore, you can find "Wine Journals."  These are notebooks organized
specifically to help people keep track of different wines they have tried.  You enter
the date and the occasion, the wine brand and varietal, and what you ate.  Then there's
a section to describe your thoughts.  This is something that is fun if you want to go
out on your own and just try.  In the end, any expert will tell you that the definition
of a "good wine" is simply one that you enjoy.