Ringtones are just sound files. many sites offer “free” ringtones that actually have hidden charges, put you on spam lists, or install other software. When using these services make sure you know what is being downloaded and what you are signing up for.
If you are familiar with using computers you can transfer the files yourself and even create your own ringtones free. If you already have the sound files connect your phone to your computer using a data connection and learn how to set a sound file as the ringtone.
For making ringtones from sound or video files you can use free audacity software. It takes a little effort to learn how to use the software but it not too bad and there are many help forums and there are specific directions for making ringtones with Audacity.