A brief tutorial on usage of chown linux command
What is this tool for..
It is to change the ownership of a file.
you should use like
chown newuser filename
To change owenership of all files and directories in current directory use *
chown newowner *
To change owner ship of all files and sub directories and files recursively
chown -R newowner .
To install extension in openoffice first go to (click on image below to go to site) Extension Section of Open Office Website.
Download the extension you want by searching on that website and copy it to any folder which you will not be deleting.
No open any one of the openoffice.org applications.
Go to Tools—> Extension Manager as shown in figure
Now click on add in the extension manager window.
Now select the downloaded extension file and click on open.
Now you can see you extension installed. Check for versions for which the extensions are valid before downloading
Steps for cropping or cutting parts of image using gimp in Linux
1) Open the image in gimp
2) Select the cropping button as shown in figure 
or go to tools–>transform tools –> crop
3) Select the area of the image you want to crop
4) Click Inside the selected area and you will see the crop image and save it.
Use GIMP to scale images in linux. Gimp is user friendly and very easy to use.
Scaling or resizing images in gimp is an easy task.
1) Open the image in gimp
2) Click on the scale button and click on image 
or go to Image –> Scale as shown in figure
You will see the options as below. Now change the size you want to scale the original image and click on save button. Now save the image.
Ok if you want to add transparent background to your picture or png files in linux these are the steps you need to follow
1) First Open the image with GIMP
2) Go to layer-> Transparency -> Add Alpha Channel
3) Now click on the fuzzy selector tool and click on the area of the image which you want to make transparent.
4)Now go to Edit –> clear as shown in figure
5) Now you can see the final image after making the background transparent.
Cheers,
Have fun with gimp