Here are a few HTML codes I know:

How to make a checkbox:
You put this in a message, etc. [BTW it doesn't fit in a blog]
To make a checkbox, put, <form><input type="checkbox" name="TypeAnything" value="TypeAnything"/>Type whatever you want.<br/>
[Press the Enter button, then,]
Type it again, put,
<form><input type="checkbox" name="Anything" value="Anything"/>Whatever</form>


How to make a login thingy:
Now, this is like a login thingy.
In order to make this login thing, put, <form>First name: <input type="text" name="firstname"/><br/> [Enter]
Last name: <input type="text" name="lastname"/></form>

How to make a password input:
This is a bubble where you put a password, to make it, put <form> Password: <input type="password" name="pwd"/></form>

How to make a gender selection thing:
For the gender selection, put <form><input type="radio" name="sex" value="male"/>Male [Enter]
<input type="radio" name="sex" value="Female"/></form>

Now that's all I have written down right now. Later on, I might make more. BTW: These are useful tools for your own site! Bye now.