To install python 3 from source, download latest python from

https://www.python.org/downloads/

Install it with

cd /usr/local/src
wget https://www.python.org/ftp/python/3.6.2/Python-3.6.2.tar.xz
tar xvf Python-3.6.2.tar.xz
cd Python-3.6.2
./configure --prefix=/usr
make
make install

To check python version

[root@server12 ~]# python3 --version
Python 3.6.2
[root@server12 ~]# 

See Python