I see many WordPress user editing their files online with the theme editor. Doing something wrong with this it is hard to step back or restore your original theme files.
I never edited any files online but prefer to use a ftp client to access any files on my host.
Using FileZilla ‚the free ftp solution‘ I can work like using any filemanager or explorer on my machine, have two windows side by side with the full tree and files on my host and the very same files on my pc as backup at home.
To get access to your site using ftp depends a bit on your hosting company, in the help files there you should be able to find out the ftp-link, username and password you have to use.
After installing FileZilla go to the server manager window and enter the required data in there. Actually very easy and after this connect to your site. -> SEE UPDATE below regarding FileZilla Servermanager and password security!!
On one side of your screen you will see the root folders and files on the host, on the other side of the screen you see files and folders of your machine.
I suggest creating on your machine a folder called ‚websites‘ and in there create another folder with the site you are just browsing via ftp.
Having done this, select all files and folders on your host and drag them to the site folder you created on your pc.
Now all your files, folders and subfolders are being copied to your pc.
It should look similar to this: (here FileZilla in German…)
You can tell Filezilla in server manger extended settings for this site to use a start folder, so use just this folder as start folder for that site and on connect the ftp client will show you two trees as above.
Double Clicking on a folder will show you the content of this folder, so go and explore your hosted files on you own machine.
In wp-content you find a plugins folder and the themes folder with subfolder of your plugins and themes.
Editing a file in your theme just right click it, choose edit and do your changes in the editor window. After saving locally FileZilla will ask you to upload the changed file automatically! But before clicking on ok, be sure to have the same folders in both windows open, otherwise it could happen that you find your sidebar.php in the root of the host and wonder that there is no change in what you edited.
One more advantage of keeping ALL WordPress files locally is, that you can easily switch the host by uploading all of the files to another server, putting a backup of you sql database there and the site will run on a new host (as soon you have changed DNS entries)
UPDATE JANUARY 2011: I do not recommend to use the Servermanager of FileZilla to store passwords of your site!! There are trojans around which could infect your machine just by surfing on an infected site.
This trojan virus could read your stored FileZilla Passwords and login, send them out and access your site to insert a malicious code into your files on the server. Look here for details:
site hacked: iframe src zxstats or bali-planet com script var zaee= on www.blogdot.de
Wordpress backup Filezilla