The 10% Plan was something that was never actually implemented. It was proposed by President Lincoln but was not accepted by the Radical Republicans in Congress. It proposed that a Southern state could form a government (and be readmitted to the Union) as soon as a number of people equal to 10% of those who voted in 1860 swore allegiance to the US.
After Lincoln was killed, Andrew Johnson became president and issued his plan for Presidential Reconstruction. It was similar to Lincoln's plan but did not have the 10% requirement. Johnson allowed states to start having constitutional conventions with delegates to be elected by loyal voters. The states had to invalidate secession, abolish slavery (ratifying the 13th Amendment) and had to refuse to pay all debts that they had incurred for the purpose of funding the war.