[HttpPut]
            [Route("UserInfo")]
            public async Task<IHttpActionResult> SetUserInfo(UserViewModel model)
            {
                if (!ModelState.IsValid)
                {
                    return BadRequest(ModelState);
                }

                var user = UserManager.FindByName(User.Identity.Name);

                user.UserName = model.UserName;
                user.Email = model.Email;
                user.FullName = model.FullName;
                user.Skype = model.Skype;
                user.PhoneNumber = model.PhoneNumber;

                SaverPhotos.SavePhoto(model);

                IdentityResult result = await UserManager.UpdateAsync(user);

                if (!result.Succeeded)
                {
                    return GetErrorResult(result);
                }

                return Ok();
        }

public class UserViewModel
    {
        public string UserName { get; set; }
        public string FullName { get; set; }
        public string Email { get; set; }
        public string Skype { get; set; }
        public string PhoneNumber { get; set; }
        public HttpPostedFileBase Avatar { get; set; }
    }

$.ajax({
                type: 'PUT',
                contentType: false,
                processData: false,
                url: '/api/account/UserInfo',
                data: data,
                beforeSend: function (xhr) {
                    var token = window.app.model.get('tokenInfo');
                    xhr.setRequestHeader("Authorization", "Bearer " + token);
                },
                success: function (response) {
                    alert("Successfully saving info!");
                },
                error: function (response) {
                    alert('Error');
                }
            });

<input type="file" name="Avatar" accept="image/png, image/jpeg, image/gif" id="profileAvatar"/>