Modify grub in ubuntu and XP to enable XP by default

After Ubuntu is installed, modify grub to enable XP to start linux by default. I am a newbie and I am very fond of cooking. Today, we installed the UBUNTU system and GRUB on the MBR, but no one in the company will use LINUX, which originally had XP, so I want to change XP to the default boot system. But I did not remember a few commands. I thought about the LS command, PWD command, and CD command. Well, these commands are very important. Yes. I need to search for information on the Internet first. Well, search for GRUB. After Ubuntu is installed on the Forum, modify grub to enable XP to start by default.
For linux, I am a cainiao, and I am very fond of food.
Today, we installed the UBUNTU system and GRUB on the MBR, but no one in the company will use LINUX, which originally had XP, so I want to change XP to the default boot system.
But I did not remember a few commands. I thought about the LS command, PWD command, and CD command. Well, these commands are very important.
Yes. I need to search for information on the Internet first.
Well, I searched GRUB and looked at it on the forum. I found GRUB information and modified the MENU. the LST file is enough. It's simple. Oh, just upload it in the/boot/grub directory. Well, wait a moment. I have to go to this directory, it is impossible to modify it in XP. LINUX.
Let me think about it. Well, UBUNTU hasn't been installed yet, but it still cannot enter the system. What should I do? Why didn't I finish the installation? I found that it had to download the installation package from the Internet when installing the system. Alas, for a long time, I ended. So it is not complete. ...
Well, isn't there a repair mode on the startup option? Well, let's try it.
On the startup option, there is a Ubuntu, kernel 2.6.12-9-386 (recovery mode). Well, this is the repair mode.
Start the system in repair mode. Well, it seems that there is a door. Enter the # prompt and have the administrator privilege. You can modify GRUB.
Run the ls command. Well, the error message is displayed, right .. Enter pwd, ah, display/root, enter the command cd/
Go to "/" and enter "ls". Enter "/boot" and "ls". grub is displayed. Enter "cd grub" and "ls ".
Menu. lst file. You can modify this file online.
Vi menu. lst, okay, but how can I modify it? It is normal to press the light mark key, but why can't I enter anything? So I pressed the INSERT key. Yes, but how can I save it? An alarm is triggered when I press any key. The ESC alarm is triggered and the press ENTER alarm is triggered. It seems that Q is exited. Why not. Whow .... I restarted and restarted N times, but I still couldn't. I checked the information online. Well, I mentioned that pressing INSERT to enter the editing status and pressing ESC to enter the command status, I tried to figure it out, but why cannot I enter the command? Weird...
I have to enter the "Number" to enter the command !!!!
The next step is to make the changes. Change timeout to 2 and DEFAULT to 3. It should be okay. Save and restart, but it is wrong ?! What's going on ?? Ah, the third item is other operating systems, other operating systems. Well, I want to change it to 4. This is the next line. Well, it doesn't matter if I change TIMEOUT to 0, I cried ..... What should I do if I cannot enter LINUX.
The UBUNTU disc in your hand is an installation disk. You don't see the option to enter the system ......
Go to the boot CD .....