View the nation you wish to send the technology to and click on "Aid" on the top part of the nation view. Then fill out the amount (maximum 50 technology) and type in your password and click "Confirm Aid Offer" to make sure the aid is alright to send, then click "Submit Foreign Aid" to send it. They will have to accept the aid offer before the money, technology, and/or soldiers are deducted from your nation's reserves.