in which group will the element with atomic no. 26 will be found..?

you just have to remember the aufbau principle....
ie the order of occurence of shells ie 1S 2S 2P 3S 3P 4S 3D 4P 5S
eg the atomic number given to me is 20 ie calcium

then its configuration is to be written ie 1S^2 2S^2 2P^6 3S^2 3P^6 4S^2
then its position will be period = 4
block = S
Group = 2

Similarly, write the electronic configuration of Iron and finding its group

Name: iron
Symbol: Fe
Atomic number: 26
Relative atomic mass (Ar): 55.845 (2)
Standard state: solid at 298 K
Colour: lustrous, metallic, greyish tinge
Classification: Metallic

Group in periodic table: 8
Group name: (none)
Period in periodic table: 4
Block in periodic table: d-block
Electron shell structure: 2.8.14.2
CAS Registry ID: 7439-89-6