Under the 'Town' tab click 'Tall Grass'. From there you can choose
a pokemon you want from the list and depending on the rarity, you
would have to wait either a few minutes or an hour. Once the radar
finds a pokemon you click on a patch of grass. If the patch of
grass doesnt contain the pokemon, the timer will reset and you will
have to wait again until you press the right grass that contains an
egg.
PS: If you want to be able to catch wild pokemon, you need to buy
an egg radar from the store (its under misc. items)
You can catch Pokemon at Route 53. Put Honey on the Honeytree and
wait until wild Pokemon appear.
However, there aren't many kinds of Pokemon there.
One more option to catch Pokemon is to use Shadow Radar. You need
to be at least trainerlevel 20 and purchase 500,000 PD to get
one
Once obtained, go to 'Shadow Radar' at Home-tab and start
hunting~!
Note that both options need Pokeball to catch! And wild Pokemon can
flee too
@Boysddontcry I don't think you can catch Pokemon using Egg Radar.
That item only allows you to get eggs from the tall grass, not
catching other Pokemon