To operate on a text object and based on your requirement, you can use any of these functions
activatetext - Activate the text
appendtext - Append the given text to the existing text
comparetextproperty - Checks the availability of all the given text property
containstextproperty - Checks the availability of one given text property
copytext - Copy text to clipboard
cuttext - Cut the text
deletetext - Deletes the text
enterstring - Genereate keyboard events as if user key-ins
getcharcount - Get the number of characters present in a text field
getcursorposition - Get the current cursor position
gettextproperty - Get the properties of text
gettextvalue - Get the text content
grabfocus - Grab the focus
inserttext - Insert a text in specified location
istextstateenabled - Verify whether the text field is enabled
mouseleftclick - Generate mouse left click event
mouserightclick - Generate mouse right click event
mousemove - Simulate mouse move event
pastetext - Paste the text from clip board to the text area
rightclick - Generate right click event
selecttextbyindexandregion - Select text by index and region
selecttextbyname - Select text by the given name
setcursorposition - Move the cursor position to the specified location
settextvalue - Sets the text value in the text field
verifypartialmatch - Verify whether the given text partially matches with the existing text
verifysettext - Verify whether the given text is same as the text available in the text field