How can i activate new ring tones and text alert tones on my sony ericsson satio phone ? also when trying to download apps it sayd redownload and when i do it shows an error !!! any help would be so gratefull cheers !!

You can set a ring tone in play view!

hope this helps please remember to take the time and give me a good rating if you appreciated my help.

Managing tracks in play view
You can manage your tracks in many ways when playing them. You can, for example,
delete a track, send a track, set a track as your ringtone or add a track to a playlist.
The following icons may appear in the touchbar when a track is playing:
Exit the play view and go back to the previous level
Go to the music library
Adjust the volume
View more commands
Delete the current track
Send the current track
Set the current track as your ringtone
Add the current track to a playlist
View track information
Minimise the music player
To delete a track
1 When the music player is open, tap > .
2 Select an option.
To send a track
1 When the music player is open, tap > .
2 Select a sending method.
To set

also can be done in personal settings:

Personal settings
You can personalise your phone by changing the standby screen, profile or themes.
Profiles
You can change settings such as the ring volume and vibrating alert to suit different
locations. You can create new profiles or change preset profiles.
To change the profile
1 Select Menu > Settings > Personal > Profiles.
2 Tap a profile and select Activate.
3 Select Back.
You can also press and then select a profile.
To edit a profile
1 Select Menu > Settings > Personal > Profiles.
2 Tap a profile and select Personalise.
3 Change the settings and select Back.
To create a new profile
1 Select Menu > Settings > Personal > Profiles.
2 Select Options > Create new.
3 Enter the settings and select Back.