I installed Slackware and It seemed to go all good, but whe I reboot it says "Missing Operating System
Insert boot diskette in drive A:, Press SPACE BAR when ready..."

I don't have a floppy drive (well, I do, but the machine has no place for me to hook it up...) What do I do? I need a boot disk, but no floppy.

You should have installed a boot loader onto the MBR when you installed Slackware (unless you were planning to use another boot loader). You can always boot off the install media and go back to the install program to install the bootloader.

I installed the LiLo bott loader... It doesn't help. Or work. I have re-installed twice and the first time I did it, It came up to the boot loaderand had me log on to some weird thing like darkstar or some thing and a prompt that I don't have anything to do...... but now it just takes me back to the insert a disk thing.
Odd. Any suggestions?

You need to make sure that the bootloader is installed on your master boot record and that it's configured with the correct location of your kernel (partition and file name). It's been awhile since I've done this, but you can check the lilo.conf file once it's set up (from the install shell) and verify that everything looks OK. If you got to "darkstar login" once that means you had it right, since that's the standard Slackware login prompt ("darkstar" is the default name of the machine if you don't give it another name during the install).

You need to boot into your system using the first installation disk, the instructions on how to do this are available onscreen when you run the disk. When you boot into your system, edit /etc/lilo.conf so that lilo is installed on /dev/hda (or whatever your main hard disk is named) and then run "/sbin/lilo" as root, then reboot. Lilo should then be installed on the mbr.