Upload the picture in your computer from your camera. Use your camera cable or if there is a memory card, use a memory card reader for connecting it to your computer.
Open the image using a image processing software. The process of increasing your picture's space varies from software from software. Generally, the option is under the 'File' option, and then clicking on the 'Open' option to upload the picture in the software. You can use Adobe Photoshop or any other software for this purpose. But make sure that your image processing software has this option.
Perform the required adjustments on the picture that you may deem necessary. Whether it maybe colour correction, exposure setting or levels adjustments, utilize them in a manner that the picture doesn't loose it's originality. All of these changes would be reflected in the image once its size is increased, so be careful while making the changes.
Choose an interpolation algorithm that you would use for your image. This feature allows you to determine how the program will fill in the missing information in an image, whose image size is increased. Most photoshop programs have a variety of algorithm selections including bicubic, smooth bicubic and nearest neighbor. Select the algorithm that best suites your image, and adjusts well with it.
Entire the desired dimension in the re-size figure box, and then click 'OK'. Once you do that, you're set algorithm would be applied on the dimensions of the image, and hence, create a large version of the original one.
Apply any post-processing features that you feel the need to. You can apply any photo filters or sharpening tools to enhance the outlook of the image. Try to keep the image the genuine so that the colours are not disturbed.
Once you're through the whole process, don't forget to check the new dimensions of the picture, as well as the size. Observe whether the size of the image increased or not, and if it didn't try going through the whole process once more just to make sure you didn't commit any mistake.