Hey :)
there are LOADS of options in this subject, jQuery gives you lots of ways. BUT to get you going, and all you will need for now, here is some advice!
Think CSS. jQuery will select like you would select in to style in CSS.
Example:
<div id="TheBox" />
<div class="TheBox" />
<p>
Ok I have a div with the ID of "TheBox", and a class of "TheBox" and a plain P – in css I would select like this…
#TheBox { /* CSS Stuff */ }
.TheBox { /* CSS Stuff */ }
p { /* CSS Stuff */ }
In jQuery you do this…
$("#TheBox")
$(".TheBox")
$("p")
you can even drill down to select things, or multipul items like in CSS…
$("#one, #two, #three")
<div id="one" />
<div id="two" />
<div id="three" />
$("#one #two)
<div id="one">
<div id="two" />
</div>
Hope that helps :)