Hacked At OS Level

my VPS has been hacked as per as the provider emailed me

Your VPS is hacked at OS level. It was running following suspicious processes and bot files were uploaded to it.

-bash-3.00# ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.0 1628 600 ? Ss 19:27 0:00 init boot
root 18326 0.0 0.1 2156 1164 ? Ss 19:27 0:00 bash
root 18354 0.0 0.0 2156 524 ? S 19:27 0:00 bash
root 18356 0.0 0.0 1524 468 ? S 19:27 0:00 sed s/.*ifcfg-venet0://
root 18357 0.0 0.0 1780 100 ? T 19:27 0:00 ls -1 bak/ifcfg-venet0:*
root 18358 0.0 0.0 0 0 ? Z 19:27 0:00 [sed] <defunct>
root 11610 0.0 0.0 1628 296 ? Ss 19:32 0:00 init boot
root 11611 0.0 0.1 2156 1200 ? S 19:32 0:00 /bin/bash /etc/rc.d/rc.sysinit
root 11625 0.0 0.0 1484 572 ? S 19:32 0:00 /sbin/initlog -r /etc/rc.d/rc.sysinit
root 11839 0.0 0.0 1456 276 ? Ss 19:32 0:00 minilogd
root 12006 0.0 0.0 2156 532 ? S 19:32 0:00 /bin/bash /etc/rc.d/rc.sysinit
root 12014 0.0 0.0 1780 104 ? T 19:32 0:00 ls ifcfg-lo ifcfg-venet0
root 12021 0.0 0.0 27104 512 ? S 19:32 0:00 sort -k 1,1 -k 2nroot 12022 0.0 0.0 1372 52 ? T 19:32 0:00 sed s/[0-9]/ &/
root 12025 0.0 0.0 1524 464 ? S 19:32 0:00 sed s/ //
root 12030 0.0 0.0 0 0 ? Z 19:32 0:00 [sed] <defunct>
root 12044 0.0 0.0 0 0 ? Z 19:32 0:00 [sed] <defunct>
root 5654 0.0 0.0 1912 392 ? Ss 22:46 0:00 vzctl: ttyp0
root 5655 0.2 0.1 2156 1248 ttyp0 Ss 22:46 0:00 -bash
root 5733 0.0 0.0 2312 764 ttyp0 R+ 22:46 0:00 ps aux
-bash-3.00# cd /usr/local/games/-bash-3.00# ls -a.
.. irc
-bash-3.00# cd irc/-bash-3.00# ls
1 12 15 18 20 23 26 29 31 34 37 4 42 45 48 50 53 56 59 61 64 8 common mfu.txt
r00t ssh
10 13 16 19 21 24 27 3 32 35 38 40 43 46 49 51 54 57 6 62 68.231.ps.22 9 full pass_file skan x
11 14 17 2 22 25 28 30 33 36 39 41 44 47 5 52 55 58 60 63 7 all go.sh ps ss-bash-3.00

how can I know what is the issue over here