Convert partition from MBR to GPT I want to install Win10 in a partition on my Macbook Pro.

Model: Macbook Pro 13' MID 2010.

I already have Windows Software Support that I downloaded from Boot Camp app.

To do so, I created a partition with 140Gb with I called "BOOTCAMP".
I need to change this partition to GPT so, to do so, I downloaded GPT fdisk.
After I installed it I opened "terminal" and run the command sudo gdisk /dev/disk0

I got this:

    Warning: Devices opened with shared lock will not have their
partition table automatically reloaded!
NOTE: Write test failed with error number 1. It will be impossible to save
changes to this disk's partition table!
You may need to deactivate System Integrity Protection to use this program. See
https://www.quora.com/How-do-I-turn-off-the-rootless-in-OS-X-El-Capitan-10-11
for more information.

Partition table scan:
  MBR: hybrid
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with hybrid MBR; using GPT.

Command (? for help): p
Disk /dev/disk0: 976773168 sectors, 465.8 GiB
Sector size (logical): 512 bytes
Disk identifier (GUID): CCEA39AF-B83B-4EB6-93F8-9A87464AB53D
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 976773134
Partitions will be aligned on 8-sector boundaries
Total free space is 262157 sectors (128.0 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1              40          409639   200.0 MiB   EF00  EFI System Partition
   2          409640       701207815   334.2 GiB   AF00  Sem nome
   3       701207816       702477351   619.9 MiB   AB00  
   4       702477352       976510983   130.7 GiB   0700  

Command (? for help): x

Expert command (? for help): n

Expert command (? for help): w

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!


The thing is, I'm afraid the process will overwrite my main partition as well.
Right now if I go to my Disk Utility I have this:


It is in Portuguese but I think you can understand the important things.

So, my question is: If I give it a "Y" in terminal, will it overwrite both of my partitions or only the partition called "BOOTCAMP"? (Will it erase my main partition?)

Thank you
If you want to do what you propose, then you are correct.

While using gdisk, you can the check GUID Partition Table (GPT) by entering the P command. After you enter the N command to change the Master Boot Record (MBR) table, you can again enter the P command. You will see the  GPT is unchanged. To see the changes to the MBR table, you will need to enter the following command before and after using gdisk.

sudo  fdisk  /dev/disk0


But, you do not want to do this for a 2010 MacBook Pro.

The 13-inch, mid 2010  MacBook Pro should install Windows 10 using the legacy BIOS boot method. The Windows Support Software for installing Windows 10 on your model Mac can be found at: Boot Camp Support Software 4.0.4033. 

Apple does not officially support Windows on your model Mac beyond version 7. The drivers for 64 bit Windows 7 are in the Boot Camp Support Software 4.0.4033  download. Fortunately, Windows 10 is designed to accept older version drivers, when current drivers are unavailable. Unfortunately, these drivers are designed for the legacy BIOS boot method. 


  Note: I am used the Boot Camp Support Software 4.0.4033 download to install 64 bit Windows 10 Pro on my 2007 iMac. Apple does not officially support any 64 bit versions of Windows on any 2007 Mac models. In spite of this, I am able to run 64 bit Windows 10 Pro on my 2007 iMac.