Sewing at Home

I bought some black pants a while ago for work, and I never got to altering them because I was always too intimidated. So yesterday, since my current ones are now unbearably faded, I set about altering them. However, even though we had a whole spool of black thread, and two spools of white, they are all mysteriously missing!! Why??!! My mom usually does alterations with the sewing machine, but she always puts the thread back in the right place. Anyway, I had a bobbin with black thread, and a spool of khaki thread, and decided I would try to sew it so that the khaki would be on the inside, and the black on the outside. So I rolled up the pants, but I didn't measure it carefully. I folded it twice, but that was too thick, and didn't fit under the presser foot, so I folded it back, but in one long fold. There was only small flecks of khaki on the outer side of the stitch, since the tension might have been too loose, but there were two problems. 1) The stitch was not very straight due to the pants moving around a bit, but most of all 2) the pants were now too short!!

This is a bobbin. It's surprising how many types of bobbins there are, but this is the usual plastic bobbin that I am working with, and that most modern-day sewing machines use (they used to be made of metal)
http://www.websters-online-dictionary.org/definitions/BOBBIN?cx=partner-pub-0939450753529744%3Av0qd01-tdlq&cof=FORID%3A9&ie=UTF-8&q=BOBBIN&sa=Search#906

This is a standard presser foot. It holds down the fabric, while the dog teeth move the fabric. (see dog teeth below)
http://www.pfaff.com/global/3194_3432.html

These are dog teeth. They are little sharp ridges that are below the cloth, and move the cloth as you sew in order to have an even stitch.
http://en.item.rakuten.com/mishin-shop/jp510/

This is what it looks like to have loose tension. Mine wasn't so extreme (and was barely noticeable), but you can see that the bottom thread shows through as it loops around the top one, and it's not pretty.
http://www.how-to-quilt.com/images/Articles/tension-loose350.jpg

I undid the stitch, which took a long long time, and by the time I was done, it was really dark, and bed time already. I called it quits for the day, and put away the machine. But I learned two things: never try to sew when you're tired and impatient, and ALWAYS check the length before you sew!

This is a seam ripper. Unfortunately mine does not have a nice bulb on the short end, causing it to snag on the cloth a lot. It takes a while to rip seams...
http://www.wikihow.com/Image:Seam-ripper-5033.jpg

Update: 3/28
My parents bought black and white thread while at the store today! Yay!! I will fix my pants soon!