It is IMPORTANT that you do not leave any open tags, such as <small> without the corresponding </small>. If you do, everything after your signature on a page will continue to be in that format.
Once you've created and saved your signature page, click the 'My Preferences' tab at the top.
In the 'Nickname' field, copy-paste your signature code.
Check the 'Raw Signatures' box right under the nickname field.
Save your preferences.
Now whenever you type 4 tildes ~~~~ your signature will appear, followed by the date. If you accidentally leave a tilde out (only type 3) it will show only your signature and if you type one too many (5 tildes) it will should only the date.
They must be no more than 19 pixels tall. If your image is too big, you have two options. The first is to re-upload it (to the same file name) in a smaller size. The second is to insert a size value into the image link. For example, [[Image:Wizardboy777_Sig.jpg]] displays this: But [[Image:Wizardboy777_Sig.jpg|19px]] displays this: Note, however, that the value you put in is the length of the image. The height will change proportionately, you may have to experiment with different length until you get a 19px high image.
The image must be exclusive to your signature. Meaning, if you want to use a skill image in your sig, copy it and re-upload to a different location (with your user name in).
The image must contain a redirect to your user page. To do this, go to the image and press the edit button, the insert the following text: #REDIRECT [[User:(insert your username)]]
Your signature should link to either your User Page or Talk Page. Some users include both of these and links to other places, such as their contributions page. To do this, on your signature page, simply put this format:
essentially creating a signature with a blue link to your user page, an orange link to your talk page, and another blue link to your Contributions page. Be careful not to let the code in your signature become too long or the sig police will catch you!